Crawl Space Downspout Extensions in Maryland
A downspout that empties right at the foundation is one of the most common reasons a crawl space stays wet no matter what's done underneath it. Extending that discharge point away from the perimeter, and specifically away from foundation vents, stops a major water source before it ever reaches the crawl space you've encapsulated.
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Why Downspouts Are a Crawl Space Problem, Not Just a Roof Problem
A roof collects a large volume of water and concentrates it at a handful of downspout locations. If any of those downspouts discharge within a few feet of the foundation, that water saturates the soil right where a crawl space's perimeter walls and vents sit. In an unsealed crawl space, that saturated soil pushes moisture straight through vents and vulnerable wall sections, working directly against a vapor barrier and vent sealing from the outside.
This is different from the discharge point problems addressed on a home's exterior drainage more broadly, this page is specifically about the downspouts and grading immediately around the crawl space perimeter and vent openings, the water path most likely to undermine an encapsulation system rather than a basement wall.
OBW's Downspout Extension Specification
- Perimeter and vent focused assessment, our inspector identifies every downspout discharging near the crawl space perimeter or within range of a foundation vent
- Buried solid pipe extension, rigid PVC piping buried below grade, not surface splash blocks, which erode and stop working within a season
- Minimum discharge distance, water is routed at least 6 to 10 feet from the foundation and away from vent openings, further where grading allows
- Positive drainage slope, every extension is graded so water flows by gravity to daylight or a suitable discharge point, no pooling at the pipe's end
One Piece of a Complete Encapsulation Plan
Downspout extensions protect the exterior side of your crawl space perimeter. Inside, a sealed vent system and vapor barrier handle the moisture that's left. OBW inspectors evaluate the whole water path, roof to foundation, and recommend only what's needed to keep your specific crawl space dry. Every downspout extension installation is backed by a written workmanship guarantee. Ask your inspector for the terms that apply to your job.
Downspouts discharging near your foundation?
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